ThieAudio has built its reputation on packing serious driver counts into shells that don’t cost a small fortune, and the Legacy 9 sits near the top of that lineup as the brand’s most ambitious hybrid IEM outside its true flagship tier. It pairs eight balanced armatures with a single dynamic driver, all wrapped in a hand-finished solid wood faceplate that makes every unit look a little different from the next.
I picked up a pair after wearing through two cheaper ThieAudio models and wanted to see whether the jump in driver count actually translated into a jump in sound quality, or whether it was mostly a spec-sheet flex. After a few weeks of daily listening on commutes and at my desk, I came away convinced this is one of the more complete-sounding IEMs in its price bracket, even if it asks a bit of patience to get the fit right.
What’s inside the shell
The Legacy 9 uses a combination of Knowles and Sonion balanced armatures alongside a 10mm nano-membrane dynamic driver for low-end reinforcement. That’s a lot of moving parts to keep in phase, and ThieAudio leans on a multi-way crossover to keep the transitions between drivers from sounding disjointed.
Dynamic driver bass
The 10mm nano-membrane driver handles sub-bass and mid-bass, giving the Legacy 9 a fuller low end than most all-BA designs manage.
Knowles dual BA
Handles the lower midrange, giving vocals body without pushing them forward too aggressively.
Sonion 2600 tweeters
Cover the upper mids and treble, adding air and detail retrieval that keeps the mix from sounding congested.
Solid wood faceplate
Every faceplate is hand-cut from genuine wood, so grain patterns and coloring vary between units.
How it actually sounds
The Legacy 9’s tuning leans warm without turning muddy. Bass has real weight and extension, but it doesn’t bleed into the mids the way some basshead-tuned IEMs do. Vocals sit slightly forward and sound natural rather than boosted, and the treble is smooth rather than sparkly, which makes the Legacy 9 forgiving with poorly mastered tracks.
Where it separates itself from cheaper multi-BA sets is in layering. On busier tracks with multiple instruments stacked together, I could still pick out individual elements without them smearing into a wall of sound. That’s the benefit of having enough drivers to split the frequency range finely.
Per Daniel R., who is an Audio Enthusiast and Head-Fi reviewer, “The Legacy 9 is proof that ThieAudio knows how to voice a hybrid without making it sound like a spec-sheet exercise. It’s warm, but it never loses composure.”
Fit and comfort
- The shells are on the larger side because of the driver count, so smaller ears may need to try a few eartip sizes before finding a seal.
- The 2-pin detachable cable is silver-plated and fairly supple, with adapters for 2.5mm, 3.5mm, and 4.4mm terminations.
- Isolation is above average for a vented hybrid design, making it usable on public transit without cranking the volume.
- Nozzle diameter is standard, so most third-party eartips fit without issue.
Source pairing and amping
One thing I wasn’t sure about going in was how demanding the Legacy 9 would be to drive properly. With eight balanced armatures and a dynamic driver sharing the load, I half expected it to need a dedicated amp to sound its best. In practice, it’s reasonably efficient and sounds full straight out of a phone’s USB-C dongle, though it does scale a little with a cleaner, more powerful source.
Pairing it with a modestly priced dongle DAC tightened up the bass noticeably compared to running it straight from a laptop’s headphone jack, which had a bit more hiss given the Legacy 9’s sensitivity. If you’re planning to use it primarily with a phone, a basic dongle DAC is a worthwhile companion purchase rather than a strict requirement.
- Works fine off a phone directly, but benefits from a clean dongle DAC
- Low output impedance sources are recommended to avoid altering the tuning
- No noticeable hiss issues when paired with quality sources
Comparing it to the rest of the Legacy line
ThieAudio’s Legacy series spans several tiers below the Legacy 9, and having spent time with the cheaper models before this one, the step up in coherence is noticeable. The lower-tier Legacy sets can sound a little thin in the lower midrange by comparison, while the Legacy 9’s extra drivers give it a fuller, more three-dimensional presentation across the board.
That said, the improvement isn’t purely about driver count. ThieAudio also spent more effort on the crossover tuning in the Legacy 9, which is part of why it avoids the slightly clinical feel that heavily multi-driver IEMs can develop when the crossover points aren’t handled carefully.
Who should consider it
If you want a single IEM that can handle bass-heavy electronic music, vocal-forward pop, and busier rock mixes without sounding like it specializes in only one genre, the Legacy 9 is a strong all-rounder. It’s not the most exciting or aggressive-sounding IEM at its price, and listeners chasing a very bright, analytical signature will probably want to look elsewhere in the ThieAudio lineup, such as the Monarch or Oracle series.
Conclusion
The Legacy 9 earns its place as ThieAudio’s flagship Legacy-series IEM by being genuinely well balanced rather than chasing a single flashy trait. The wood faceplates give it a distinct look, the nine-driver hybrid configuration delivers a full and detailed sound, and the price puts it within reach of enthusiasts who aren’t ready to spend four figures on a pair of IEMs. You can check current availability and full specs on Linsoul’s official Legacy 9 page or read more listener impressions over on Head-Fi.
FAQ
Is the ThieAudio Legacy 9 good for bass-heavy genres?
Yes. The 10mm dynamic driver gives it noticeably more low-end weight than most all-BA IEMs at a similar price, without the bass overwhelming the rest of the mix.
Does the wood faceplate affect durability?
The wood is sealed and finished for daily use, and most owners report no issues with chipping or fading under normal handling. Extreme temperature swings or moisture exposure should still be avoided, as with any wood product.
What cable and connector does it use?
It ships with a detachable 2-pin silver-plated cable and includes swappable plugs for 2.5mm, 3.5mm, and 4.4mm outputs, so it works with most sources out of the box.
How does it compare to ThieAudio’s Monarch series?
The Legacy 9 is warmer and more relaxed, while the Monarch line generally pushes for a more neutral or analytical signature at a higher price point. Choose the Legacy 9 if you prioritize a musical, forgiving tuning over ultimate resolution.
Ryan
CS degree · 20+ years hands-on hardware testing